Drilling bit



June 30, 1931,. G. B. LUDERBACK 1,812,210

DRILMNG BIT,

Filed May 28, 1928 2 Sheets-Sheet l y 1 .1.1 W w .lune 30, 1931. G. B.LOUDERBACK 1,812,210

DRILLING BIT Filed May 28, 1928 2 Sheets-Sheet 2 obliquely guiding andpositioning the cutting blades.

The tool is provided with a pair of oblique bifurcated cutting blades 21and 22 which are transversely grooved at their upper ends to formflanges 23, for engaging asimilarly grooved blade head 24, tov be`longitudinally positioned thereby. They are also provided withlongitudinal flanges 25 on their leading faces. The blade head moves upand down in the shallow rectangular recesses 18. The longitudinal iangesof the blades engage the respective channels 20, and are constrained'thereby to move obliquely. As bladehead 24 is moved downward, the bladesare fed obliquaely trom the endof the tool; their upper ends meanwhiletraversing the blade head in. engagement with its cross groove.

The feeding mechanism which is the subject matter of the presentinvention, comprisesV a piston rod 26', extending from blade head 24 andcarrying a piston 27 at the top. ItV is the hydraulic pressure exertedagainst this piston from above that causes the blades. to be advanced,and which resists their upward thrust. The piston works within a`cylinder 28, having an inward low one-way valve 29, in its: upper head30; and an angularly spaced arrangement' of outward flow one-way valves31, ofsubstantially equivalent area, is provided in its: lower head 32.A tubular shell 33, spaced from both cylinder 28 and housing 15,encloses the cylinder and its inlet val-ve.

Cylinder 28 and shell 33 respectively are screwed into and uponfatubular member 34, and the latter is screwed upon a central boss formedat the upper ends oi' the united body halves 11 and 12. Within the boreof lmember" 34, belowl the head of cylinder 28 and slightly spacedtherefrom, is a pump block 35. In cooperation with the adjacent parts,this block forms the closure of a chamber 3G beneath it. Ther pump blockis provided with three angularly spaced one-way pressure pumpsthecyl-indrical bores of which are: shown at 87. The piston rods 38 ofthese: pumps extend downwardly through theblock into` chamber 36, andtherein are surrounded by helical compression springs 39' for normallymaintaining the pump plungers 4t) atthe bottom of theirstrokes. j

'Ehe' above described feed mechanism is` actuated by means of apair oflongitudinal plunger rods 41,A normally projecting from the lower end ofthe tool, and terminating in a shoe 42. at the` bottom. These lrodsextend intoi chamber 36 and are united therein by a ring 43,` which isof suicient diameter to` also engage the lower ends of' pump rods 41'.The plunger rods are free to slide up and down in recesses 19, and astrong helical compression spring v44, surrounding rod 26, tends to keepthe rods pressed down as shown in Figure 2.

Packing boxes 45 and 46 pack rod 26 where it passes through cylinderhead 32 and pump block 35 respectively.

Cylinder 28, space 48 beneath it, and space 49 surrounding it, arefilled with a light oil or other suitable fluid; and a series ofangularly spaced small passages 50 connect spaces 481 and 49.v l/Vhenpump plungers 40 are pushed upwardly, oil is forced thereby throughpassage 50, space 49, and valve 29 into cylinder 28 above' piston 27.The hydraulic pressure forces the piston downwardly to advance thecutting blades of the tool. Oil beneath piston 27 is forced out from thecylinder, through valves 31.

YVhen the tool is inoperation, the euttin-g` bla-des are advanced to theposition shown inA Figure 3. At that time the weightV of the tool andtool string is largely, if not entirely, .upon the ci'itting blades;Aand plungery rods 41 are pushed part way into the tool for the reasonthat shoe 42' rests' upon the bottom of drill hole 47. After the bladeshave become worn, and it is desired tol advance them further, the toolifi-rstV is raised to allow the plunger rods to become. fully extended,andV then is lowered to push the rods in again. This operation works.pump plungers 40, andputs a hydraulic pressure upon piston 27, in themanner explained above. Y By reason of the relatively very smalldiameter of the pump plungers, a heavy hydra-ulic pressure may beexerted in. this way upon piston 2,7. For similar reasons the movementof piston 27 is only a small iraction of the stroke of the pump`plungers.. The operation just described may be repeated, to cause anydesired advancement of the. blades.

Circulating water is ied to the blades through bore 1,7, space 51between shell 33 and housing 15, and the small passages 52, leading fromspace 51 `to the lowerl endsof body halves 11 and 12,. and dischargingyin front of the respective. cutting blades.

Havingv thus fullydescribed the construction and operation of myinvention, I claim:

1. A drilling; bit comprising ;v a body; cutting blades adapted forbeing advanced. from the body obliquely to its axis; a rain adapted foradvancing said blades; longitudinally slidable plunger rods normallyprojecting from the end of said bit; and means whereby an hydraulic`pressure may be exerted upon said ram by the longitudinal sliding'ofsaid rods. Y Y

2. A` drilling bit, comprising; a body; cutting blades adapted for beingadvanced from j the body obl'iquely to its axis; an' hydraulic ramadaptedV for advancing said blades longitudinally slidable plungerrodsinormally projecting from the end of said bit; and pump Y meansinterposedY said f rods and the ram whereby an hydraulic pressure mayexertedv upon the ram by the longitudinal sliding of the rods.

3. A drillingbit com rising;a body; f ting blades adapted'k for eingadvanced from f Y the body obliquely to its axis; a cylinder'within thebody .a piston, slidable within said cylf inder, having a piston rodconnected to said blades for advancing them; a' pump within the bodywhereby an hydraulicpressure may be exerted upon said piston; andplungerrods normally projecting from the end of said bit,Y d adaptedbyrlongitudinal reciprocation toopV Y l erate said pump.

4. A drilling bitv comprising; a body;,cut l,

ting blades adapted by longitudinal sliding to be advancedy from `theend; ofthe body oba liquely to its axis a cylinder Within the body; Y ja piston, slidable Withinsaid eylinder,'having v a piston rodoperatively connected' to said blades for'advancing them; a pump VWithin,thebody,. operatively connected to said cylin v der, whereby anhydraulic pressure may be` exerted upon'said piston; plunger rods nor-ymally projecting from'the end of said bit, adapted by longitudinalreciprocationto op- Y erate said pump; and a spring,` opposing thelongitudinal movement of' said plunger rods i and adapted to restorethem to their normal position. Y y a y .Y

5. A Vdrilling bit comprising;a body; movable cutting blades projectingfrom thebody ;V longitudinally slidable plunger rods that nor-V mallyproject from the end of said'b'ody; and

hydraulic pressure means for progressively advancing said blades; saidmeans being Y adapted for actuationby reciprocating said rods.

6. A drilling bit comprising; abody; mov- I able cutting bladesprojecting from the body,

and adapted for. being advanced obliquely tov the axis thereof;longitudinally slidable plungerrods that normally project fromk the endof said body.; and hydraulic pressurel means for progressivelyadvancingV said blades; said meansbeing adapted for actuation byreciprocating lsald rods.'k

GEORGE iafLoulniRBACK.` j A

